Coms stable on Ms2x 3.3.1 but constant drop out on pre3.4b10

[slow_hemi6]

Hi I have for a long time run my previous engine on 3.3.1 and never had issues with coms. I put in my new engine and I upgraded firmare to pre3.4b10. It loaded fine and I had an issue of needing to change from com1 to my usual com3 to get going but unfortunately the coms constantly drop out. I reloaded 3.3.1 and the coms are fine again. I can log for extended periods and use veal without issues on 3.3.1. I need to get my engine fully run in so I'll stay on 3.3.1 till that is done. After that I will try to use pre 3.4b10 again.
This is an extract from my project folder from when I started to change over. Any clues there?

TSAppDebugextract.txt

[slow_hemi6]

This is what I get from a normal 5 minute run with 3.3.1.

3.3.1 5minrun.txt

[slow_hemi6]

Bueller, Bueller, anyone?

[LT401Vette]

I would probably need a comm debug log and msq to tell much.

Is it any event that triggers the drop outs or just sitting there not running?

[slow_hemi6]

No event that I can see. It seems to do it when driving or sitting. Not constantly but fairly often.

[mega_user]

I have a similar problem. MS3 will work with a a STI labs serial card. But will not work with USB - serial cable purchased from EFi analytics.
But MS2 and MS1 will work with USB - serial cable purchased from EFi analytics and not with STI labs serial card.
Win7 I5 IBM laptop.
All on the latest firmware.

The good old IBM T30 on XP with serial port will work on all platforms without problems.

So there is a problem in the USB drivers / communication.